film techniques - Breaking a whiskey glass with your bare hands: how would this have been done?

In Broken City, there's a scene where the character, Jack Valliant, breaks his whiskey glass by squeezing it with his bare hands. I'd first like to know if this is actually physically possible. Second, I'd like to know how this might have been done in the movie especially from a safety POV.

Here are a couple of screenshots of the event.

I assume that the glass is a prop (that he actually drinks out of) which shatters very easily. However, won't it still be a safety hazard? While the actor appears to have mitigated some of the risk by cleverly concealing his face behind his arm, it appears to only be partial. Moreover, the bald guy (commissioner) is unprotected and has shards even falling behind him. These two are clearly not stuntmen either. How would this situation have been handled?